The present invention relates generally to material handling equipment, including but not limited to mobile machinery of the type used for material handling jobs that require moving or positioning of a load. In particular, the present invention relates to a load handler with a modular frame and the manufacture and assembly of the frame and loader and components that may be used therein.
In construction jobs, it is desirable to lift heavy loads such as equipment, building materials, or earth, and to move, position or place the loads at other locations. This may require movement of a load high above and forward from the loader. Load handling vehicles, also referred to as loaders, loader vehicles or load handlers, employ pivoting booms that may be raised or lowered about a pivot point on the loader frame, and may be telescoped to move the load to the desired position. Attachments for the booms may be used for performing various jobs. For example, fork and bucket attachments may be used for moving materials like bricks or earth. Other attachments may be used for pouring concrete, handling roof trusses, boring holes in the earth, or other tasks.
The capability of loader vehicles is measured in some respects by how heavy a load it can lift and how high it can lift a load. For example, loaders may lift loads weighing up to twenty to sixty thousand pounds or more, to heights of up to twenty to one hundred feet or higher. The factors affecting the loader capability include, for example, the strength of the boom structure, the power of hydraulic cylinders for lifting and telescoping the boom, and the stability of the loader vehicle against tipping over. The stability depends on factors such as the weight of the loader vehicle, the positioning of the boom pivot point on the vehicle, the front to back and side to side spacing of the wheels, and the center of gravity of the load and vehicle.
In use, a load handling vehicle is subjected to tremendous stress forces resulting from the positioning of heavy loads at the end of the boom. These stress forces include twisting forces about the longitudinal axis of the frame of the vehicle. Depending on the work site conditions, the load handler may have to travel over or stand on uneven surfaces while carrying or positioning the load. This may increase the stress forces, such as due to leveling forces exerted by stabilizing hydraulic cylinders acting between the axles and the vehicle frame. Consequently, the vehicle frame may be subjected to compound bending and twisting stress forces due to the heavy loads and movement. The vehicle frame is desirably constructed with sufficient stiffness and torsion strength to withstand these forces without experiencing unacceptable deformation.
To achieve sufficient stiffness and torsion strength, frames for loader vehicles have been built using a box-shaped generally closed overall frame cross-section configuration. Although such a configuration provides good stiffness, the box shape may require that the boom pivot point be positioned relatively high. A relatively lower boom pivot point may be desirable to lower the center of gravity to increase stability of the vehicle. Some load handlers are configured to achieve a low boom pivot point by mounting the vehicle engine and operator cab to the sides of the vehicle with the boom nestled between them in the boom""s lowered position. This configuration also provides a good field of vision for the operator in many uses of the load handier. However, to accommodate the lower boom position, the top of the box-shaped closed overall frame cross-section configuration may have to be opened up to an extent, thus adversely affecting stiffness and torsion strength. For example, such opened frames may lose stiffness and torsion strength particularly with respect to twisting forces along the vehicle front to rear longitudinal axis, with twisting occurring along the length of the frame""s longitudinal structural beam members, or side rails.
In addition, the frames of load handling vehicles are commonly made in a unitary construction with components particularly designed for a particular vehicle capability. The frames are assembled using a xe2x80x9ccellxe2x80x9d type manufacturing process in which all the components for the frame of the vehicle are brought to a location and all the components are assembled at that location. Such an assembly process is relatively inefficient in that it requires dedicated floor space for extended periods of lead time during assembly.
The present invention provides a load handling vehicle, a structural frame and method of assembly using modular components. A frame is provided that has a low pivot point for a boom that may be lowered to a position within the frame. The frame has left and right side rails, and front and rear cross rails, each having a closed cross-section construction. The side rails and cross rails are modular and the cross rails of a selected size are configured to fit a plurality of sizes of side rails, such that the same size cross rails may be used to construct a variety sizes and capabilities of load handling vehicles in a flow type manufacturing process.
In one aspect, a structural beam is provided having plates interconnected along their lengths to form the beam having a box-shaped closed cross-section having a perimeter generally along the widths of the plates and forming a beam cavity within the perimeter. A first plate has a width greater than the width of an opposed second plate, and the plates are positioned to form a plurality of welding land inside corners along the length of the beam. A corresponding weld is formed simultaneously with a single pass at all of the welding land inside corners along the lengths thereof to interconnect the plates to form the structural beam.
In one aspect a motorized four-wheeled telescoping boom load handling vehicle has a modular longitudinally extending frame. The boom is pivotally secured to the carriage at one end and pivotally supports load handling means such as a fork carriage or crane hook or grapple, or the like, at the other end. Cylinders may be provided for elevating and lowering the boom relative to the carriage and for extending and retracting the boom segments. The various power means can be actuated selectively to extend and retract the boom and to raise and lower the boom.
In another aspect, a leveling system may be provided to maintain the frame level through all operating positions.
In another aspect, a frame is provided that has a low pivot point for a boom that may be lowered to a position within the frame. The frame includes closed section shaped side rails and cross rails. In another aspect of the invention, the frame is for a load handling vehicle.
In another aspect, a structural frame is provided having: a left side rail and a right side rail, each having a closed cross-section and a front end and a rear end; a front cross rail having a closed cross-section is rigidly affixed between the side rails at a forward location; and a rear cross rail having a closed cross-section is rigidly affixed between the side rails at a rearward location.
In another aspect, the structural frame side rails include: a first plate, a second plate, a third plate and a fourth plate; each of the plates having respectively a length, a width, and a thickness; the first and second plates being arranged in an opposed position to one another, and the second and third plates being arranged in an opposed position to one another; the plates being interconnected along their lengths to form the rail having a box-shaped cross-section having a perimeter generally along the widths of the plates and having a rail cavity within the perimeter; the first plate width being greater than the second plate width, and the plates are positioned with the widths of the third and fourth plates extending between, abutting and positioned generally traverse to the widths of the first and second plates, to form a plurality of welding land inside corners along the length of the side rails; a corresponding weld is formed at each of said welding land inside corners along the lengths thereof to interconnect the plates.
In another aspect, the frame is adapted for a load handling vehicle and the rails include the side rails of the vehicle.
In another aspect, the side rails and cross rails are modular and the cross rails of a selected size are configured to fit a plurality of sizes of side rails, such that the same size cross rails may be used to construct a variety sizes and capabilities of load handling vehicles.
In another aspect a method for manufacturing a structural frame apparatus is provided including the steps of: assembling modular components of a frame; stocking the components for later use; selecting a capability for a frame; choosing the modular components for configuring the selected frame; retrieving from stock components for a subassembly of a frame; assembling the components for the selected subassembly; and if the product assembly is not completed, moving the product to the next assembly station and returning to and repeating the step of retrieving components for another subassembly and continuing the process until the frame assembly is completed.
In another aspect, the subassembly made by such method is a frame for a load handling vehicle.
In another aspect a structural beam is provided having a first plate, a second plate, a third plate and a fourth plate, each plate having respectively a length, a width, and a thickness, the first and second plates arranged in an opposed position to one another, the second and third plates arranged in an opposed position to one another, and the plates interconnected along their lengths to form the beam having a box-shaped closed cross-section having a perimeter generally along the widths of the plates and forming a beam cavity within the perimeter. The first plate width is greater than the second plate width, and the plates are positioned with the widths of the third and fourth plates extending between, abutting and positioned generally traverse to the widths of the first and second plates, to form a plurality of welding land inside corners along the length of the beam. A corresponding weld is formed at each of the welding land inside corners along the lengths thereof to interconnect the plates to form the structural beam.
In another aspect, a method for manufacturing a structural beam is provided including the steps of providing a first plate, a second plate, a third plate and a fourth plate. Each of said plates has respectively a length, a width, and a thickness. The first plate width is greater than the second plate width. The first and second plates are arranged in an opposed position to one another, and the second and third plates being arranged in an opposed position to one another, such that the plates are positioned with the widths of the third and fourth plates extending between, abutting and positioned generally traverse to the widths of said first and second plates, to form a plurality of welding land inside corners along the length of the beam. A corresponding weld is simultaneously formed at all of the welding land inside corners along the lengths thereof to interconnect the plates along their lengths to form the beam having a box-shaped closed cross-section, a perimeter generally along the widths of the plates, and a beam cavity within said perimeter.
These and other features and advantages of the invention will be more clearly understood from the following detailed description and drawings of preferred embodiments of the present invention.